Dogs help others raise them. He said to give it to me in a few days. Can I call the police?

In this case, you can call the police.

It should be noted that before calling the police, you need to prepare some evidence to prove that you are the legal owner of the dog and that you have reached an agreement with the foster family. Such evidence can include signed written agreements, emails, text messages, social media messages, etc.

Secondly, you should try to contact the foster care agency to understand the dog's situation and ensure its safety. If the surrogate mother refuses to return the dog, you should take action as soon as possible to ensure that the dog will not be hurt or unnecessarily troubled.